The assessment of influence of different nitrogen compounds and time on germination of Lupinus angustifolius seeds and chemical composition of final products

The aim of the research was to determine changes in the chemical composition in lupin seeds during seed germination in a solution containing selected nitrogen compounds. Blue lupin seeds of the Neptun cultivar were germinated for 3 or 4 days in darkness, at 24°C in 1% solutions containing the following nitrogen compounds: urea, nitric acid, ammonium sulphate, methionine or yeast extract. The control consisted of seeds germinated in water. The presence of all nitrogen sources has resulted in a poorer growth of the sprouts as compared to seeds germinated in water. There was a significant increase in the true protein content as well as a significant decrease in the content of crude ash and alkaloids in the germinated seeds. The seeds germinated for 4 days had significantly higher total protein content and significantly lower content of nitrogen-free extract compounds and oligosaccharides as compared to the seeds germinated for 3 days. A significant influence of the nitrogen source on the concentration of some amino acids was found. Cystine was found to be absent in seeds germinated in the nitric acid solution, while there occurred a twofold increase in the cystine content and a fivefold increase in the methionine content in seeds germinated in the aqueous solution of methionine and an 50% increase in the cystine concentration was observed in seeds germinated in the yeast extract and ammonium sulphate solution. Methionine and cystine were the limiting amino acids in all the samples, accept of seeds germinated in the methionine solution were it was valine. Aqueous solutions of ammonium sulphate and yeast extract were found to have the most advantageous influence on the chemical composition of lupin germination products.